Download Immune System

Immune System
3/10
______________________________________________
Objectives:
1. Describe the components and functions of the immune system.
2. Differentiate among the types of immunity.
3. Describe the etiology, incidence, diagnosis, prognosis and management of the
patient with HIV/AIDS.
4. Discuss standard precautions (universal precautions).
5. Discuss the development and significance of latex allergies.
6. Review allergic and anaphylactic responses.
_______________________________________________________________
Readings:
1. Lewis, Medical-Surgical Nursing: 7th edition, chapters 13-15; chapter 59, pp.
1542-1549; chapter 65, pp. 1702-1711 and pp. 1716-1723.
Lewis, 6th edition, chapters 12-14; chapter 57, pp. 1563-1569; chapter 63, pp.
1724-1733 and pp. 1739-1744.
2. CDC - Divisions of HIV/AIDS Prevention, Web site,
http://www.cdc.gov/hiv/dhap.htm
3. “Nitrile and other non-latex glove allergies,”
http://www.gloveuniversity.com/gloveallergy/nitrileallergy.php
4. "Taking HAART: How to Support Patients with HIV/AIDS", Sandra Gracia
Jones, Nursing2004,
http://findarticles.com/p/articles/mi_qa3689/is_200406/ai_n9433799
5. “Collaborative model shows early success in battling MRSA: early
participants cut number of infections by about 85%,” HealthCare Benchmarks
and Quality Improvement, December 2005,
http://findarticles.com/p/articles/mi_m0NUZ/is_12_12/ai_n15932704
_______________________________________________________________________
Please use the following outline along with the readings to complete the objectives of the
course.
Immune System
Definition - Network of cells and organs that work together to defend the body
against attacks of “foreign” invaders
-bacteria
-viruses
-parasites
-fungi
Properties of the Immune System
-Specificity
-Memory
-Self-recognition
Antigens
-a “foreign” particle that can trigger an immune response
-in abnormal situations, the immune system can mistake
“self” for “non-self” and attack = Autoimmune Disease;
-or the immune system can respond inappropriately to a seemingly harmless
substance such as ragweed pollen = Allergy
Structure of the Immune System
Lymphoid organs
-home to lymphocytes, key players to the immune
system
Bone Marrow
Thymus
Lymphocytes travel throughout the body, using either
the blood vessels or the lymphatic vessels
The lymphatic vessels carry lymph – a clear fluid
that bathes the body’s tissues
Lymph nodes – small bean-shaped tissue with
specialized compartments where lymphocytes
congregate and encounter antigens
-neck
-axilla
-abdomen
-groin
Spleen
-fist sized organ upper left abdomen
-specialized compartment of lymphocytes
Lymphoid tissue
Found many parts of the body, especially
in territories that are a gateway to the body
-linings of GI tract, lungs
-tonsils, adenoids, appendix
Lymphocytes
B cells
Work by secreting soluble substances called
Antibodies into the body’s fluid
B cell encounters a triggering antigen = produces many
Plasma cells = factory for producing antibody
An antibody matches an antigen. When they interlock,
the antibody marks the antigen for destruction.
Antibodies belong to a family of large molecules called
Immunoglobulins.
IgG – coats microbes to speed up their
uptake by other cells in the immune
system
IgM – effective in killing bacteria
IgA - concentrates in body fluids – tears,
saliva, secretions of GI tract and
respiratory system – guarding
entrances to the body
IgE – protect against parasites, also
responsible for symptoms of allergy
T Cells
-some direct and regulate the immune responses
-others are killer cells that attack cells that are
infected or cancerous
-secrete chemical messengers – lymphokines –
which bind to the target cells and encourage cell
activity, direct cell traffic, destroy target cells,
and arouse phagocytes
Natural Killer Cells
-another kind of lethal lymphocyte
-will attack any foe
Phagocytes
-cell eaters
-large white cells that can swallow and digest
microbes and other foreign particles
-Monocytes are phagocytes that circulate in the
blood. When they migrate into the tissues, they
develop into Macrophages – scavengers – rid
the body of worn out cells and debris and display
bits of foreign antigen in a way that attracts the
matching lymphocyte
Granulocytes
-lymphocyte that contains granules that are filled
with potent chemicals that allow them to destroy
microorganisms
-Neutrophil
-Eosinophil
-Basophil
-mast cell – twin to basophil except not in
blood, but in lungs, skin, tongue, and
linings of the nose and intestinal tract
where it is responsible for symptoms
of allergies
Complement System
-made up of 25 body chemicals that work together
to “complement” the action of antibodies in
destroying bacteria
-also helps rid the body of antibody-coated
antigens (antigen-antibody complexes)
-Complement proteins cause the blood vessels to
become dilated and then leaky, contributing to
redness, warmth, swelling, pain, and loss of
function that characterizes an inflammatory
response
Mounting an Immune Response
Microbes first must get by the body’s external
Armor
-skin
-membranes lining the body’s gateways
-these are also rich in scavenger cells and
IgA antibodies
Then they must get past the body’s non-specific
defenses, ready to attack without regard to
specific antigen markers
-scavenger cells
-natural killer (NK) cells
-complement
Then they confront specific weapons:
Antibodies are triggered when a B cell encounters its matching antigen
The B cell takes in the antigen and digests it and displays antigen fragments
bound to its own distinctive marker molecules
The combination of antigen fragment and marker molecule attracts the help of a
mature, matching T cell.
Lymphokines secreted by the T cell allow the B cell to multiply and mature into
antibody-producing plasma cells
Released into the bloodstream, antibodies lock onto matching antigens. These
antigen-antibody complexes are soon eliminated by the liver and the spleen
T cells are mobilized when they encounter a cell such as a macrophage or a B cell
that has ingested an antigen and is displaying antigen fragments to its marker
molecules
Lymphokines help the T cell mature
The T cell alerted and activated secretes lymphokines
Some lymphokines spur the growth of more T cells
Some T cells become killer cells and tract down body cells infected by viruses
Some lymphokines attract immune cells – fresh macrophages, granulocytes, and
other lymphocytes to the site of the infection
Types of Immunity
Natural – exists without prior contact with antigen
Active Acquired Immunity – results from invasion of microorganisms and
subsequent development of antibodies. With each re-invasion, body responds
more rapidly.
-naturally or through inoculation of less virulent
antigen
-immunity takes time, but is long lasting
Passive Acquired Immunity – host receives antibodies to antigen rather than
synthesizing them.
-naturally through transfer across placenta
-injection of serum antibodies
-short-lived, did not synthesize, has no memory of
antigen
Effects of Aging on Immune System
Decline in immune system
-increase in tumors
-greater susceptibility to infections
-bone marrow relatively unaffected
-decrease in Thymus tissue
-T & B cells show deficiencies in activation,
transit time through cell cycle and subsequent
differentiation
-delayed hypersensitivity response
Altered Immune Responses
Hypersensitivity
Autoimmunity
Immunodeficiency
___________________________________________________________
Acquired Immunodeficiency Syndrome
(From NIAID)
The acquired immunodeficiency syndrome (AIDS) was first recognized in 1981
and has since become a major worldwide pandemic. Abundant evidence indicates
that AIDS is caused by the human immunodeficiency virus (HIV), which was
discovered in 1983. By leading to the destruction and/or functional impairment of
cells of the immune system, notably CD4+ T cells, HIV progressively destroys the
body's ability to fight infections and certain cancers.
Why is there overwhelming scientific consensus that HIV causes AIDS?
Before HIV infection became widespread in the human population, AIDS-like
syndromes occurred extremely rarely, and almost exclusively in individuals with
known causes of immune suppression, such as chemotherapy and underlying
cancers of certain types. A marked increase in unusual infections and cancers
characteristic of severe immune suppression was first recognized in the early
1980s in homosexual men who had been otherwise healthy and had no recognized
cause for immune suppression. An infectious cause of AIDS was suggested by
geographic clustering of cases, links among cases by sexual contact, mother-toinfant transmission, and transmission by blood transfusion. Isolation of the HIV
from patients with AIDS strongly suggested that this virus was the cause of AIDS.
Since the early 1980s, HIV and AIDS have been repeatedly linked in time, place
and population group; the appearance of HIV in the blood supply has preceded or
coincided with the occurrence of AIDS cases in every country and region where
AIDS has been noted. Individuals of all ages from many risk groups – including
men who have sex with men, infants born to HIV-infected mothers, heterosexual
women and men, hemophiliacs, recipients of blood and blood products, healthcare
workers and others occupationally exposed to HIV-tainted blood, and male and
female injection drug users – have all developed AIDS with only one common
denominator: infection with HIV.
HIV destroys CD4+ T cells, which are crucial to the normal function of the human
immune system. In fact, depletion of CD4+ T cells in HIV-infected individuals is
an extremely powerful predictor of the development of AIDS. Studies of
thousands of individuals have revealed that most HIV-infected people carry the
virus for years before enough damage is done to the immune system for AIDS to
develop; however, with time, a near-perfect correlation has been found between
infection with HIV and the subsequent development of AIDS. Recently developed,
sensitive tests have shown a strong correlation between the amount of HIV in the
blood and the subsequent decline in CD4+ T cell numbers and development of
AIDS. Furthermore, reducing the amount of virus in the body with anti-HIV drugs
can slow this immune destruction.
(From NIAID Fact Sheet)
HIV/AIDS Statistics
For updated statistics see
http://www.cdc.gov/hiv/dhap.htm
---------------------------------------------------------